General Bio - The Chemical Foundation of Life (Ch. 2)

Vocabulary flashcards covering matter, atoms, isotopes, the periodic table, Bohr model, bonds, and mole concepts from the lecture notes.

Matter

Anything that has mass and occupies space.

Element

A pure substance with unique properties, composed of one type of atom; represented by a chemical symbol.

Chemical symbol

A one- or two-letter abbreviation for an element (e.g., S, Ca, C).

Atom

The smallest unit of an element that retains its chemical properties; composed of a nucleus and orbiting electrons.

Nucleus

The center of the atom that contains protons and neutrons.

Electron

A negatively charged subatomic particle orbiting the nucleus; symbol e−.

Electron shell / Orbital

Regions around the nucleus where electrons reside, organized in energy levels with capacity limits.

Proton

A positively charged subatomic particle in the nucleus; defines the atomic number.

Neutron

A neutral subatomic particle in the nucleus; contributes to atomic mass.

Atomic Mass Unit (amu)

A unit of mass for atoms; roughly the mass of a proton or neutron; defined as 1/12 the mass of carbon-12.

Atomic number

Number of protons in an atom; defines the element.

Mass number

Total number of protons and neutrons in an atom.

Isotope

Form of an element with the same number of protons but different numbers of neutrons.

12C (Carbon-12)

Carbon isotope with mass number 12; major natural form (~99%).

13C (Carbon-13)

Carbon-13 isotope with mass number 13; about 1% natural abundance.

14C (Carbon-14)

Radioactive carbon isotope used in radiometric dating; trace amounts in nature.

Hydrogen isotopes

Isotopes of hydrogen: 1H, 2H (deuterium), 3H (tritium); same proton number, different neutrons and masses.

Radioisotope

Unstable isotope that emits radiation as it decays.

Radiometric dating

Technique using decay of radioactive isotopes to estimate the age of materials (e.g., fossils).

Carbon dating

A type of radiometric dating using carbon isotopes, especially 14C.

Periodic Table

Organization of elements by increasing atomic number and recurring properties.

Noble gases (Group 18)

Elements with full valence shells and very low reactivity.

Bohr model

Early atomic model with protons in the nucleus and electrons in circular orbits at specific distances; energy levels.

Electron shell

Energy levels around the nucleus that hold electrons; capacity varies by shell.

Valence shell

Outermost electron shell; fullness leads to stability; Group 18 has full valence shells.

Covalent bond

Bond formed by sharing electrons between atoms.

Ionic bond

Bond formed by transfer of electrons creating oppositely charged ions (e.g., NaCl).

Chemical bond

Attractive force that links atoms to form molecules and compounds.

Chemical formula

Notation showing the number of each type of atom in a molecule (e.g., H2O).

Structural formula

Diagram showing the arrangement of atoms in a molecule.

Mole (mol)

Amount of substance containing 6.02 x 10^23 entities.

Avogadro's number

6.02 x 10^23; the number of units per mole.

Molecular mass / molecular weight

Sum of the atomic masses in a molecule (in amu); roughly equal to grams per mole.

1 mole = molecular mass in grams

Mass in grams of 1 mole of a substance equals its molecular mass in amu.

Hydrogen peroxide (H2O2) mol mass

H2O2 has a molecular mass of 34 amu; 1 mole weighs 34 g.

Stoichiometry example

Balanced equation: 2 H2O2 → 2 H2O + O2; relates moles of reactants and products.

Table salt (NaCl) formation

Sodium and chlorine form NaCl by achieving a full outer electron shell (ionic bonding).

Carbon is central to life

Life is carbon-based; carbon-containing substances are not all organic.

Carbon atomic number

Carbon has atomic number 6.

Carbon isotopes natural abundance

Approximately 99% 12C, ~1% 13C, trace amounts of 14C in nature.

Carbon-12 mass

12C has an atomic mass of 12 amu.

Carbon-12 atomic mass (overall)

The overall atomic mass of carbon including isotopes is about 12.011 amu.

Neutrons calculation

Neutrons = mass number − atomic number.

Neutral atom electrons

In a neutral atom, the number of electrons equals the number of protons.